Test detects Brucella in goat's milk.

Goat milk sold in the United States may soon be better protected against brucellosis-causing bacteria, thanks to recent research conducted by USDA-ARS scientists. A new test for detecting B. melitensis in bulk goat milk relies on an adaptation of an enzyme-linked immunoassay (ELISA) that the investigators developed in 1984 for testing cattle for B. abortus.

B. melitensis, one of six known species of Brucella that induces abortions in animals, mainly infects sheep and goats. In humans, B. melitensis infection causes Malta fever and headaches. Few cases of this infection in goats have occurred in the United States since 1972. But it is essential that vigilance be maintained to prevent the introduction of the bacteria into the country. B. melitensis is particularly common in Latin America, central and southwest Asia, and the Mediterranean region.

Dairy goat milk is slowly gaining popularity due to its high protein and low cholesterol levels, as well as its compatibility for people who are intolerant to cow's milk. About 1 million goats are raised for milk and cheese production in the United States.

The new assay, which detects B. melitensis antibodies, identified one goat with a high concentration of infection in a herd of more than 1,600 animals, and one goat with a low concentration in a herd of 50 animals. It also correctly identified all 13 positive and 134 negative bulk milk samples tested. The researchers recommend that herds be sampled in groups of 50 animals or fewer for bulk milk testing. They next intend to miniaturize the test and apply for a patent.

Brucellosis is not very common in the United States, where 100 to 200 cases occur each year. But brucellosis can be very common in countries where animal disease control programs have not reduced the amount of disease among animals. Although brucellosis can be found worldwide, it is more common in countries that do not have good standardized and effective public health and domestic animal health programs. These high-risk countries include those in the Mediterranean Basin (Portugal, Spain, Southern France, Italy, Greece, Turkey and North Africa), South and Central America, Eastern Europe, Asia, Africa, the Caribbean and the Middle East. Unpasteurized cheeses, sometimes called "village cheeses," from these areas may be a risk for tourists.

Further information. Louisa Tabatabai, USDA-ARS National Animal Disease Center, P.O. Box 70, 2300 Dayton Ave., Ames, IA 50010; phone: [phone]; fax: [phone]; email: [e-mail].